We have obtained evidence indicating that the unconjugated N- hydroxylated derivatives of the bladder carcinogens 4-aminobiphenyl, 1- naphthylamine, and 2-naphthylamine are the proximate or urinary carcinogenic metabolites of these amines in the dog, and that they play a key role in the etiology of bladder cancer in this species. We propose to determine if the source of the unconjugated N-hydroxylamine metabolites of these three amines in the bladder are derived from the enzymatic hydrolysis of their O-sulfonate and/or O-glucuronide esters formed in the liver for renal excretion. The chemical synthesis of these esters will be undertaken. It remains to be established if the N-hydroxylamines are also the ultimate carcinogens (triggering the carcinogenic response in the target tissue) or whether they require a further enzymatic (e.g. esterification) or a non-enzymatic (e.g. oxidation to the nitroso derivative) transformation. Since it would seem likely that a chemical carcinogen must react with some constituent of the target tissue in order to induce neoplasia a comparative study of the type and extent of the interaction of the N-hydroxylamines, their O-sulfonate and/or O- glucuronide esters, and nitroso compounds with selected cellular macromolecules and constituents isolated from dog bladder mucosa both in vivo and in vitro will be undertaken.